# A student releases a toy car to roll down a ramp, as shown. The student measures the distance l from the middle of the car as it is released to the bottom of the ramp and the distance s travelled along the straight section before the car stops. He also measures the time t taken to travel the distance s.

Chapter 32, Exam-style Questions #7

A student releases a toy car to roll down a ramp, as shown. The student measures the distance l from the middle of the car as it is released to the bottom of the ramp and the distance s travelled along the straight section before the car stops. He also measures the time t taken to travel the distance s. He then repeats the experiment using a different value of l.
The student obtained readings with l = 40 and 60 cm, taking each reading for s and t twice. The readings were:
l = 40.0 cm: values for s were 124 and 130 cm; values for t were 4.6 and 4.8 s
l = 60.0 cm: values for s were 186 and 194 cm; values for t were 4.9 and 5.2 s.
a. For the smaller value of l, obtain a value for:
i. The average value of s
ii. The absolute and percentage uncertainty in the value of s
iii. The average value of t
iv. The absolute and percentage uncertainty in the value of t.
b. i. For both values of l, calculate the average speed v of the car along the straight section of track using the relationship v = s/t .
ii. Justify the number of significant figures that you have given for your values of v.
c. i. It is suggested that s is proportional to l. Explain whether the readings support this relationship.
ii. (HARDER) It is suggested that v2 is proportional to l. Explain whether the readings support this relationship.
d. Describe four sources of uncertainty or limitations of the procedure for this experiment.
e. Describe four improvements that could be made to this experiment. You may suggest the use of other apparatus or different procedures.

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